One claim is that Hearst believed that his extensive timber holdings were threatened by the invention of the decorticator, which he feared would allow hemp to become a very cheap substitute for the paper pulp that was used in the newspaper industry.[106][109] Modern science suggests that this fear would have been unfounded. Improvements of the decorticators in the 1930s, machines that separate the fibers from the hemp stem, could not make hemp fiber a very cheap substitute for fibers from other sources due to the fact that the long strong fibers are only found in the bast, the outer part of the stem. Only about 1/3 of the stem are long and strong fibers.[33][106][110]

Hemp was used extensively by the United States during World War II. Uniforms, canvas, and rope were among the main textiles created from the hemp plant at this time.[118] Much of the hemp used was cultivated in Kentucky and the Midwest. During World War II, the U.S. produced a short 1942 film, Hemp for Victory, promoting hemp as a necessary crop to win the war.